Geotravese tatseis: One of the most significant components of trans-euroasian megatransform

Article type :

Tectonic & Seismotectonic

Location :

International Geological Congress,oslo 2008

Fulltext :

The Tatseis geotravese was acquired in order to obtain qualitatively new information and some additional data. It crossed in NW-SE direction the European part of Russia and the Volga-Ural petroliferous province including the giant Romashkino oil field. The main purpose was to examine the structure of the sedimentary cover and the entire crust in the North Tatar Arch, Kazan–Kazhim Aulacogen, Kotel’nich Arch, and southeastern Moscow Syneclise and to compare these structures with the South Tatar oil-bearing arch.
The Tatseis-2003 geotraverse (more than 1000 km long) crossed the Nizhni Novgorod and Kirov regions, as well as the Mari-El, Tatar, and Bashkir republics. In its southeastern part, near Sterlitamak, the profile was coordinated with the Uralseis-1995 geotraverse. So, that has provided integrated information along ~1600-km-length profile extending from the Urals to the Moscow Syneclise.
The following technique was applied for field acquisition: asymmetric spread of 12000 m length and 240 active channels; maximal source-to-receiver distance - 10 000 m; receiver spacing - 50 m; source points spacing - 100 m; fold coverage - 60. The telemetric system INPUT/OUTPUT SYSTEM TWO was used as recording system. The record length was 20 s with a sample rate of 4 ms. A group of 5 powerful seismic vibrators Hemi-50 with the maximal force of 23 t was used as source. The sweep parameters specified in the course of tests were as follows: initial frequency 6 Hz; final frequency 64 Hz; sweep length 20 s. It should be noted that the applied technique and equipment provided high-quality results.
The main feature of the wave field is presence of inclined SE rising events at large time intervals. Those events show distinct zoning distribution: they are mainly observed in the southeastern segment of the geotraverse (interval 100–430 km) where oilfields are located.
The lower segments of inclined reflectors adjoin the lower near-horizontal stratified crust, cross it in some places, and flatten at the Moho boundary level. Locally, these reflectors cross the Moho boundary and penetrate the upper mantle. This is particularly distinct at the interval of 430-480 km (t0=15-19 s).
Thus, the results of the performed work indicate:
1) The correctness of target formulation and survey planning, as well as the optimal use of technical means and methodical approaches.
2) The presence of relationship between the petroleum potential of sedimentary cover and the structure of the earth crust and mantle